Lubricating grease containing paraffin wax



Patented Dec. 12, 1950 LUBRICATING GREASE CONTAINING PARAFFIN WAX- Rosemary OHalloran, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 9, 1948, Serial No. 64,417

6 Claims.

The present invention relates to an improved lubricating grease containing parafiin wax. More particularly, it pertains to a soap-thickened lubricating grease having improved high temperature life by reason of the inclusion of appreciable quantities of parafiin wax.

Numerous suggestions have been made in the prior art for the use of various quantities of parafiin wax in lubricants of various types. It has been suggested, that steam engine lubricating compounds may be compounded of refined petroleum oil, lime water, resin oil, graphite and wax, as in Patent No. 1,222,128. A lubricant for automobile springs has been suggested, composed of paraffin, beeswax, castor oil and graphite, as in Patent No. 1,735,368. A solid rease-like material for use on roll necks of steel roll mills has been suggested, composed of paraflin wax, petroleum oil, rosin, degras, lime and soapstone, as in Patent No. 1,780,315. A ball bearing lubricant which is adapted to liquefy on agitation ha been suggested as composed of wax and lubricating oil, as in Patent No. 2,056,594.

A saw blade lubricant has been suggested, composed of paraflin wax of high melting point combined with a small amount of soda grease and minor quantities of petrolatum and aluminum stearate. See the patent to Flood, No. 2,4 9,713. This product is essentially a wax, modified with soap and not a grease. It has no true grease structure.

The composition of the present invention bears some resemblance in its ingredients to that described in the last mentioned patent. but is quite different in that it is predominantly a grease, having a true grease or colloidal structure, consisting of lubricating oil thickened with conventional soaps. To the grease is added a minor amount, such as 1 to 20% by weight, preferably 2 to 15%, based on the total composition, of ordinary paraffin wax such as scale wax of moderately low melting point. The waxes preferred are high molecular weight straight chain hydrocarbons of a chain length in the neighborhood of about 30 carbon atoms, for example, 16 to 40 carbon atoms. A wax having a melting point between about 110 and 135 F. is preferred, particularly one melting between 120 and 130 F.

The invention will be more fully understood by reference to specific examples.

Example I A composition was prepared consisting of 4% by weight of the combined soda and barium soaps of hydrogenated fish oil fatty acids of about 12 to 22 carbon atoms, combined with 75.6% of a non-paraffinic treated coastal distillate lubricating oil of about 500 S. U. S. viscosity at 100 F., or 55 S. U. S. at 210 F., of scale wax from Panhandle crude oil having a melting point of about 2 125 F., and 0.4% of phenyl alpha naphthylamine as an oxidation inhibitor. The grease of the above example was subjected to the ABEC-NLGI spindle test operating at 10,000 R. P.- M. and at 250 F. test temperature as described in NLGI Technical Bulletin No. 5. The grease performed satisfactorily in this severe high temperature spindle test for 839 hours. The same composition without the paraffin wax had a spindle life of only 218 hours.

Example II Another grease was prepared which contained 13% of the soda and barium soaps of hydrogenated fish oil acids (HO Hydrofol acids) having a high Cm content, in a base stock consisting of of a solvent extract/ed Panhandle oil and 15% of a coastal distillate oil. The grease also contained 0.4% phenyl alpha naphthalamine as an oxidation inhibitor. Scale wax of F. melting point was blended into portions of the above grease at F. .Samples of grease containing no wax and 2.5% wax were subjected to the ABEC-NLGI spindle test, with the following results:

The above data show that whereas the grease which contained no wax had a spindle life of only 54. hours greater than the reference test, the grease which contained 2.5% wax had a spindle life of 254 hours greater than the reference test. The reference was a soda-barium grease made with extracted Rodessa oil of high viscosity index (113) and about 43 S. S. U. viscosity at 210 F. The soap content totaled 13 the soda soap-barium soap ratio being about 18 to 1.

The invention is applicable to straight soda greases having soap contents of 5 to 30%, to high temperature calcium base greases of similar soap content, to' aluminum soap greases and also to various other conventional single or mixed base greases, as well as to acetylene black and other structure black greases. The quantity of parafiin wax employed should not be more than 40% in any case, and in general should not be more than 20%, based on the weight of the total composition. As little as 1% of paraflin wax is use- -ful, but quantities of at least 2% are ordinarily preferred, the most useful range being from about 2 to 15% paraffin wax, 5 to 30% soap, and

55 to 93% of mineral base lubricating oil. The oil may be of any suitable type and viscosity, but in general it should have a viscosity of not less than about 100 nor more than about 1000 S. U. S. at 100 F.

Conventional antioxidants such as phe y alpha naphthylamine, and phenyl beta naphthylamine, and the like, may be used, quantities of 0.1 to about 1% being preferred, and other common additives such as stringiness agents, metal deactivators, viscosity index improvers, extreme pressure agents, and the like, may also be added, as will be understood by those skilled in the art.

By the addition of paraiiin wax to greases of this character. the advantageous high temperature lubricating properties of such waxes are imparted to the grease without thereby imparting also the undesirable low pour properties of waxy oils. That is to say, that a grease prepared from a dewaxed oil, thickened with conventional soap thickeners and. having parafiin wax added thereto, is a more satisfactory lubricant than one prepared from an oil which has not been dewaxed.

The coastal distillate which was employed in Example I was derived from a non-waxy crude. In the case of dewaxed oils obtained from waxy crudes, the added wax is not the total wax removed in dewaxing, but only the scale wax fraction thereof. That there is a difierence is borne out by a comparison of the low temperature properties of greases containing added scale wax with those predicted from correlation curves. The greases were prepared in the same manner and with about the same soap content as the soda-barium greases described in Examples I and 11. Data are shown below:

I From correlation of low temperature torque with viscosity and pour point of base oil.

The above data show that the greases containing added wax perform in an unexpected manner, which is different from that of greases prepared from non-dewaxed oil. Correlations which were satisfactory for prior art greases are, therefore, entirely unsatisfactory for the greases of this invention.

As regards the quantity of wax which is employed, the data given above show that the addition of about 2.5% wax gave an improvement of about 200 hours in spindle life. The lower limit should, therefore, be about 1.0%. upper limit is about 20%, and a preferred concentration may range from about 2% to about 15%. These limits refer to greases prepared in a mineral oil base.

Synthetic ester base greases have also been prepared, using 20% by weight of lithium stearate, 20% Panhandle scale wax and di 2-ethylhexy1 sebacate. The grease is of excellent structure and stability. These greases have shown a spindle life of 350 hours at the high temperature of 300 F. which is considered exceptional.

Ordinarily, a small increase in the pour point The of an oil greatly increases the torque of a grease prepared from such oil. This is not true, however, 'in greases which have their pour point in creased by adding paraffin wax, according to this invention. Oil with added parainn wax is considerably better in this respect than oil having a high initial wax content, probably due to the presence of amorphous or microcrystalline waxes in the latter. Petrolatums and petrolatum waxes appear to be undesirable in greases of this character.

The addition of wax is practical with soda soap greases, soda-lime greases, and the like, but is not of utility with calcium soap greases which require water to stabilize them and which have very poor high temperature properties. In sodalime greases where they are used, the proportions of soda soap to lime soap are preferably 3 to l to 5 to 1, by weight. In all cases, the alkali metal soap should predominate and in many cases a straight alkali metal soap, such as soda soap in mineral oil or lithium soap in dibasic acid ester oils will be used as the thickening agent.

What is claimed is:

l. A lubricating grease consisting essentially of 50 to by weight of lubricating oil of about to 1,000 S. S. U. viscosity at 100 F., said 011 consisting of at least one oil composition selected from the group which consists of mineral base lubricating oils and synthetic ester oils of the dibasic aliphatic acid branched chain alkyl ester type, 5 to 30% of predominantly alkali metal soap of fatty acids having 12 to 22 carbon atoms, and 2 to 15% or parafiin wax having a melting point between about and F.

2. A composition as in claim 1 to which is added 0.1 to 1% weight of a phenyl naphthylamine as an oxidation inhibitor.

3. A composition as in claim 1 wherein the lubricating oil is a mineral base oil.

4. A composition as in claim 1 wherein the lubricating oil is a synthetic dibasic aliphatic acid branched chain alkyl ester.

5. A lubricating grease composition consisting essentially of 14% by wei ht of predominantly alkali metal soap, 75.6% mineral lubricating oil, 10% parafin wax having a melting point between about 110 and 135 F., and 0.4% of an oxidation inhibitor.

6. A lubricating grease consisting essentially of mineral lubricating oil of 100 to 1000 S. U. S. viscosity at 100 F. thickened to a grease consistency with predominantly alkali metal soaps of substantially saturated fatty acids, said composi tion containing 2 to 5% by weight, based on the total composition, of paraffin wax havingamelting point between about 110 and 135 F. to improve high temperature life in anti-friction bearings.

ROSEMARY OI-IALLORAN.

EENDEES CKTED The following file of this patent:

T631625 are of record in the 

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF 50 TO 90% BY WEIGHT OF LUBRICATING OIL OF ABOUT 100 TO 1,000 S.S.U. VISCOSITY OF 100 DEGREES F SAID OIL CONSISTING OF AT LEAST ONE OIL COMPOSITION SELECTED FROM THE GROUP WHICH CONSISTS OF MINERAL BASE LUBRICATING OIL S AN DSYNTHETIC ESTER OILS OF THE DIBASIC ALIPHATIC ACID BRANCHED CHAIN ALKYL ESTER TYPE, 5 TO 30% OF PREDOMINANTLY ALKALI METAL SOAP OF FATTY ACIDS HAVING 12 TO 22 CARBON ATOMS, AND 2 TO 15% OF PARAFFIN WAX HAVING A MELTING POINT BETWEEN ABOUT 110* AND 135*F. 